All the papers, treatises etc. Literature is the art of written work and can, in some circumstances, refer exclusively to published sources. The word literature literally means "things made from letters" and the pars pro toto term "letters" is sometimes used to signify "literature," as in the figures of speech "arts and letters" and "man of letters. Literature may consist of texts based on factual information, as well as on original imagination, such as polemical works as well as autobiography, and reflective essays as well as belles-lettres. Literature can be classified according to historical periods, genres, and political influences. The concept of genre, which earlier was limited, has broadened over the centuries.